1. Field of Invention
The present invention relates to a semiconductor device, and more particularly to a lateral diffused metal oxide semiconductor (LDMOS) device for an electrostatic discharge (ESD) protection circuit.
2. Description of Related Art
ESD is the main factor of electrical overstress (EOS) which causes damage to most of electronic devices or systems. Such damage can result in the permanent damage of semiconductor devices and computer systems, so that the circuit function of ICs is affected and the operation of electronic products is abnormal.
In a deep submicron semiconductor process, the ESD tolerance is getting worse as dimensions of devices are getting smaller. Hence, the design for ESD protection has been taken into account when designing ICs. Usually the ESD tolerance for commercially available ICs is required to pass the human body mode (HBM) test at 2 kV and the machine model (MM) test at 200 V.
In order to sustain the above-mentioned high-voltage ESD tests, the large-sized ESD protection device for ICs is usually applied. This large-sized device is designed as a multi-finger shape in the layout to save the chip area as much as possible.
However, for the frequently used LDMOS device in power management, at the moment, the multi-finger LDMOS device still cannot pass the HBM test at 2 kV and the MM test at 200 V. Therefore, a LDMOS device having enough ESD tolerance is deeply desired for an ESD protection circuit.